The present invention relates to a novel electrical bushing assembly and method of making the same, and more specifically to a novel assembly comprising a metal connector or terminal element enclosed by a body or sheath of insulating material molded thereon.
It will be appreciated that bushing assemblies of the type contemplated herein may be used in a wide variety of electrical installations where it is desired to provide an insulated connection through a support or a wall of a housing or enclosure. Examples of such installations include transformers, switchgear and the like.
Heretofore, electrical bushing assemblies of the general type contemplated herein have been produced by first casting the metal electrical element or terminal member and then placing such member in a mold and pressure molding insulating material therearound. In order to leave the conductor element or terminal member with exposed ends, the element is formed so that such ends project from the mold cavity. At areas where the electrical element projects from the mold cavity, it is desired that a very close and tight fit be obtained between the mold and the element so that the element acts as a shutoff and insulating material will not leak out of the cavity during a molding operation.
It will be apreciated that electrical conductor or terminal elements of the type contemplated herein are usually cast in sand molds. Such a process usually does not produce the close tolerances required to enable the element to have the desired tight fit with the mold body. Heretofore, it has been the general pracitice to process such cast terminal elements by machining the desired area to obtain the necessary tolerances. In certain instances, it is difficult to obtain the desired tolerances even with such additional machining of the terminal element particularly when a relatively soft metal such as certain aluminum alloys is used in casting the element or terminal member.